Efficient in vivo removal of solubility tag to improve the bacterial production of soluble, bioactive human IGF-1.

Human insulin-like growth factor-1 (hIGF-1) is a non-glycosylated polypeptide hormone that plays a crucial role in prenatal and postnatal growth. Recently, various engineered variants of hIGF-1 have been created to enhance protein stability and activity. However, challenges persist in the production process, including yield, purification, and production costs. In this study, we simultaneously expressed active TEV protease and His-tagged hIGF-1 fused with the TrxA solubility tag in SHuffle T7 Express and Rosetta-gami 2(DE3) strains to assess expression yield and in vivo digestion of the soluble TrxA-free His-tagged hIGF-1 fusion protein. Our findings revealed efficient expression of recombinant TrxA-TEVs-His.hIGF-1, with successful digestion by TEV protease to release TrxA-free His-tagged hIGF-1 in both strains. However, the SHuffle strain exhibited higher expression levels and TEV protease functionality under optimized conditions. Furthermore, bioactivity assays of the purified TrxA-free His-tagged hIGF-1 demonstrated comparable activity to a commercial hIGF-1. This study developed a simple and feasible method for producing and purifying soluble, active recombinant hIGF-1 without any solubility tag through effective in vivo cleavage. By maintaining protein activity, this method is expected to simplify downstream processing and reduce both the time and cost of protein production.